Proactive engine start (pes)

ABSTRACT

A method and system are provided for controlling transfer switch operations in a power distribution system. The method and system involve monitoring an electrical parameter of an electrical signal from a first power source associated with supplying power to a load; determining whether the electrical parameter satisfies a parameter threshold; selecting to increment or decrement a count value in accordance with the determination; and responsive to determining that the count value satisfies a first count threshold, initiating a start signal to start operation of a second power source to supply power to the load. The electrical parameter can be voltage or frequency, or other parameter(s) from which a power quality of the electrical signal may be evaluated. The electrical signal can be a single or polyphase electrical signal.

TECHNICAL FIELD

The present disclosure relates to a power management system and method,and more particularly, to a transfer switch system and method forpredicting power conditions on a primary power source to facilitateproactive control of the start or stop operation of a secondary orbackup power source in a power distribution system.

BACKGROUND

Power distribution systems are employed to provide electric power tooperate equipment in various applications. These applications mayrequire nearly constant supply of reliable electrical power to operateeffectively. For example, hospitals may require a constant and reliablesupply of electricity to ensure medical equipment in operating rooms andthe like function when needed. Further, food retailers such assupermarkets and grocery stores may require a constant and reliablesupply of electricity to properly operate refrigeration systemsassociated with display cases and freezers to prevent food spoilage.

While utility companies generally provide electrical power consistentlyand reliably, such power is sometimes interrupted due to inclementweather, unforeseen accidents, maintenance or other factors. Electricalpower consumers seeking to mitigate or avoid even minor interruptions intheir power supply often rely on generators and other backup systems tosupply electrical power during periods when electrical service from autility company is interrupted. Transfer switches enable these consumersto switch between a primary electrical source (e.g., from a utilitycompany) and a secondary electrical source (e.g., a generator or otherbackup system) when one source becomes unreliable or requiresmaintenance.

SUMMARY

A method and system are provided for controlling operations in a powerdistribution system. The method and system involve monitoring anelectrical parameter of an electrical signal from a first power sourceassociated with supplying power to a load; determining whether theelectrical parameter satisfies a parameter threshold; selecting toincrement or decrement a count value in accordance with thedetermination; and responsive to determining that the count valuesatisfies a first count threshold, initiating a start signal to startoperation of a second power source to supply power to the load. Theelectrical parameter can be voltage, frequency, or other parameter(s)from which a power quality of the electrical signal may be evaluated.The electrical signal can be a single or polyphase electrical signal.

In various embodiments, the count value can be incremented ordecremented by an amount according to a value of the electricalparameter. The count value can be incremented if the electricalparameter of the electrical signal satisfies the parameter threshold,and can be decremented if the electrical parameter of the electricalsignal does not satisfy the parameter threshold. An amount to incrementthe count value can be different from an amount to decrement the countvalue.

In a further embodiment, the parameter threshold can comprise aplurality of parameter threshold ranges having associated therewithdifferent increment or decrement amounts. The determining operation candetermine a parameter threshold range for the electrical signal from theplurality of parameter threshold ranges. The selecting operation canincrement or decrement the count value by an amount associated with thedetermined parameter threshold range from the plurality of parameterthreshold ranges.

In another embodiment, the action can comprise of initiating a startsignal to start operation of a second power source for supplying powerto the load. The method and system can further involve, after initiatingthe start signal, controlling a switch to transfer responsibility ofsupplying power to the load from the first power source to the secondpower source. In yet a further embodiment, the second power source canbe connected to supply power to the load. The method and system canfurther involve continuing the performance of the monitoring,determining and selecting operations over time to update the countvalue; and when the count value satisfies a second count threshold,initiating a stop signal to stop operation of the second power sourceand controlling the switch to transfer responsibility of supplying powerto the load from the second power source back to the first power source.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed description of the disclosure, briefly summarized above,may be had by reference to various embodiments, some of which areillustrated in the appended drawings. While the appended drawingsillustrate select embodiments of this disclosure, these drawings are notto be considered limiting of its scope, for the disclosure may admit toother equally effective embodiments.

FIG. 1 is a block diagram illustrating an example automatic transferswitch system for switching a power supply to a load from one powersource to another power source, in accordance with an embodiment.

FIG. 2 are examples of two graphs, one of which illustrates a monitoredelectrical parameter of an electrical signal (e.g., voltage) from apower source over time, and the other of which illustrates a countvalue, which may change according to the monitored electrical parameter,over time, in accordance with an embodiment.

FIG. 3 is a flow chart illustrating example operations of a method bywhich an engine start signal is initiated to start a power source in atransfer switching scenario, in accordance with an embodiment.

FIG. 4 is a flow chart illustrating example operations of a method bywhich an engine stop signal is initiated to stop a power source atransfer switching scenario, in accordance with an embodiment.

FIG. 5 is a flow chart illustrating an example method of controllingoperations in a power distribution system, in accordance with anembodiment.

Identical reference numerals have been used, where possible, todesignate identical elements that are common to the figures. However,elements disclosed in one embodiment may be beneficially utilized onother embodiments without specific recitation.

DETAILED DESCRIPTION

The present disclosure is directed to a method and system for powermanagement, such as controlling transfer switch operations and/or otherpower management operations. In a power distribution system, apower-quality measuring or monitoring device, such as for example, anautomatic transfer switch, may detect a power outage condition for aprimary power source and then responsively transfer the power supply toa load from the primary power source to a secondary or backup powersource. However, the secondary power source takes time to turn ON, whichmay result in a discontinuous supply of power to the load when switchingover from the primary power source to the secondary power source. Theautomatic transfer switch system of the present disclosure can employ asimple and effective approach, which also is light on memory usage andprocessor clock cycles, to predict power conditions on a primary powersource (e.g., imminent power outage or failure, etc.) to facilitateproactive control of the start or stop operation of the secondary orbackup power source and other transfer switch operations. The transferswitch system of the present disclosure can facilitate continuous supplyof electric power by turning ON the secondary power source and switchingto the secondary power source prior to an outage or other failure on theprimary power source.

For example, in various embodiments, the transfer switch system of thepresent disclosure can employ a counting scheme to track a current stateof the electric power supplied by the primary power source. Inparticular, a count value of a counter circuit is either incremented ordecremented over time according to the acceptability or unacceptabilityof a monitored electrical parameter (e.g., voltage, frequency, etc.) ofthe electrical signal being supplied from the primary power source. Aparameter threshold can be used to gauge the acceptability orunacceptability of the monitored electrical parameter. The count valuecan reflect a current operational state of the electric power suppliedby the primary power source (e.g., reliable or unreliable), and astart-count threshold can be used to predict a likelihood of an imminentoutage or failure of the primary power source. When the count valuesatisfies the start-count threshold, the automatic transfer switchsystem can automatically initiate an engine start signal to start theoperation of the secondary power source (e.g., turn ON the power sourceor its engine), and implement other transfer switch operations toswitchover the power supply to the load from the primary power source tothe secondary power source.

In a further embodiment, a stop-count threshold also can be employed topredict when the electric power supplied by the primary power source isor has become reliable (or stable). When the count value satisfies thestop-count threshold, the automatic transfer switch system canautomatically initiate an engine stop signal to stop the operation ofthe secondary power source (e.g., turn OFF the power source or itsengine), and implement other transfer switch operations to switchoverthe power supply to the load from the secondary power source back to theprimary power source.

These and other features of the present disclosure will be described infurther detail below with reference to the example figures.

FIG. 1 illustrates a block diagram of an example of an automatictransfer switch system 100, in accordance with an embodiment. Thetransfer switch system 100 can selectively couple a load 50 to either afirst power source 10 or a second power source 20. For example, thefirst power source 10 can be a primary power source, and the secondpower source 20 can be a secondary power source. The primary powersource can be provided by a power utility (e.g., via the electric grid)and the secondary power source can be provided by a backup generator(s)or other electric power generating system which needs to be turned ON(or the like) to operate. In other examples, the primary power source(s)and/or the secondary power source(s) can be other types of powersupplies.

As shown in FIG. 1 , the first power source 10 is coupled to thetransfer switch system 100 via a first conductor 30A, the second powersource 20 is coupled to the transfer switch system 100 via a secondconductor 30B, and the transfer switch system 100 is coupled to the load50 via an output conductor 30C. In general, the first power source 10and the second power source 20 can provide electric power in the form ofan electric signal. In various embodiments, the electric signal can, forexample, be an alternating current (AC) voltage signal.

While the power sources 10 and 20, the conductors 30A through 30C, andthe load 50 are shown as a single-phase system in FIG. 1 , otherconfigurations can be utilized in other examples. For instance, thepower sources 10, 20, the conductors 30A through 30C, and/or the load 50can be configured as a polyphase system in other examples, such as athree-phase system. In a single-phase system, the conductors 30A through30C carry a single electric signal. In a three-phase system, threeconductors 30A through 30C may each include multiple conductors tofacilitate carrying three separate electric signals of the samefrequency at different phases.

As further shown in FIG. 1 , the transfer switch system 100 can includea switch(s) 110, controller(s) 120, memory 130, sensor(s) 140, andcommunication device(s) 150. The various components of the transferswitch system 100 may be interconnected via a bus system to facilitatecommunication therebetween.

The switch 110 can be operated to selectively connect the first powersource 10 or the second power source 20 to the load 50. The switch 110can include one or more electrical devices. For example, such additionalelectrical devices may comprise one or more electromechanicalcontactors, solid state devices, circuit breaker devices, and/or othersuitable devices for electric power switching. In one example, theswitch 110 can include a solenoid that activates an electrical contactto move between a connection to the first conductor 30A and a connectionto the second conductor 30B. Other examples are also possible. Forexample, such electrical devices may be internal or external to thetransfer switch system 100.

The switch 110 can be operably switched between multiple states. Forexample, in a first state, the switch 110 can connect the first powersource 10 to the load 50. In a second state, the switch 110 can connectthe second power source 20 to the load 50.

The controller 120 is configured to control the various components ofthe transfer switch system 100 and perform various operations associatedwith the switching of the power supply to a load from one power sourceto another power source. For example, the controller 120 can control theswitch 110 to selectively switch between the first state and the secondstate. Therefore, the controller 120 may provide control signals to theswitch 110, which selectively control the state of the switch 110 toconnect either the first power source 10 or the second power source 20to the load 50. The controller 120 can control the switch 110 based onan analysis of the electric signal transmitted on the first conductor30A from the first source 10 to the load 50. In particular, thecontroller 120 can monitor the electric signal (or electrical parametersthereof) on the first conductor 30A for certain conditions over time,which can indicate that it may be beneficial to switch the load 50 fromthe first power source 10 to the second power source 20 (e.g., an outageor failure of the first power source 10 is likely to occur).

The controller 120 also can initiate engine control signals forcontrolling the operations of the second power source 20. The controlsignals may include an engine start signal for starting operations ofthe second power source 20 (e.g., turn ON), and an engine stop signalfor stopping operations of the second power source 20 (e.g., turn OFF orinitiate SLEEP or STANDBY MODE). The controller 120 can initiate theengine start signal or engine stop signal based on a power qualityanalysis of the electric signal transmitted on the first conductor 30Afrom the first power source 10 to the load 50. In particular, thecontroller 120 can monitor the electric signal, particularly itselectrical parameter(s), over time on the first conductor 30A forcertain conditions, which indicate that it may be beneficial to startoperation of the second power source 20 (e.g., an outage or failure ofthe first power source 10 is likely to occur), or stop operation of thesecond power source 20 (e.g., electric power supplied by the first powersource 10 is or has become reliable or stable).

For example, in various embodiments, the controller 120 can employ acounter circuit with a count value, which is incremented or decrementedaccording to the state of the monitored electrical parameter(s), totrack certain conditions on the electrical power supply over time. Thecount value, which is updated over time, can help to predict a currentoperational state of the first power source 10, such as the reliabilityof the power source (e.g., stable) or the unreliability of the powersource (e.g., unstable, imminent outage or failure of the power source,or etc.). The counter circuit can employ variable weights whichincrement or decrement based on the electrical parameter or valuethereof. For example, the amount to increment or decrement the countvalue of the counter circuit can be based on a parameter threshold(s)for the monitored electrical parameter or value thereof. Based on thecount value, the controller can proactively initiate an engine start orstop signal, control the switch 110 to change the source of the powersupply (e.g., 10 or 20) to the load 50, and control or perform otheroperations as part of the transfer switching operations of the transferswitch system 100.

In particular, when electric power is supplied to the load 50 from thefirst power source and the count value satisfies a start-countthreshold, the controller 120 can initiate the engine start signal andother transfer switch operations to switch the power supply to the load50 from the first power source 10 to the second power source 20. Whenelectric power is supplied from the second power source 20 and the countvalue satisfies a stop-count threshold, the controller 120 can initiatean engine stop signal and other transfer switch operations to switch thepower supply to the load 50 from the second power source 20 back to thefirst power source 10. The control signals as well as other informationmay be communicated, via the communication device 150, to the secondpower source 20 or other devices or systems, under control of thecontroller 120.

To monitor the electric signal (and its electrical parameter(s)) on thefirst conductor 30A, the controller 120 is coupled to the firstconductor 30A via the sensor 140. The sensor 140 may be internal (i.e.,integral) or external to the controller 120. The sensor 140 can sensethe electric signal transmitted on the first conductor 30A and providean indication of one or more electrical parameters of the electricsignal (e.g., a magnitude or frequency of current, voltage, power, etc.)to the controller 120. Various different types of sensors may beutilized. In one example, the sensor 140 can include a currenttransformer coupled to the first conductor 30A. In such an example, ascurrent flows through the first conductor 30A, the current transformerinduces a current in the sensor 140 that is proportional to the currentflowing through the first conductor 30A. The sensor 140 and/or thecontroller 120 may then determine or derive, from the induced current, avoltage or current of the electric signal transmitted on the firstconductor 30A from the first power source 10 to the load 50. Otherexamples are also possible. The transfer switch system 100 can includean additional one of sensor(s) 130, if desired, to monitor theelectrical signal (and its electrical parameter(s)) on the secondconductor 30B in a similar manner.

The controller 120 can be, for example, a processor such as amicrocontroller, a microprocessor, an application specific integratedcircuit (ASIC) device, field programmable gate array (FPGA),programmable logic controller (PLC) or other processing system or thelike. In FIG. 1 , the controller 120 is further communicatively coupledto the memory 130.

The memory 130 can store any data required by the controller 120 fordetecting and predicting conditions of the primary power source 112,initiating a power transfer, or executing any other functionalityincluding those described herein. For example, the memory 130 can storecount value(s) 132 for a counter circuit(s), parameter threshold(s) 134,count threshold(s) 136, application code (e.g., main functionalityfirmware), initialization parameters, boot code, code for executingalgorithms, code for monitoring, detecting, determining and/orpredicting conditions of a power source, code for initiating enginestart or stop signal, code for setting user defined thresholds foralgorithms, check sums to determine whether code is corrupted, lockcodes, and/or other data. This data can be stored in the memory 130 atthe factory, manually entered via an input/output device (not shown), orremotely downloaded via the input/output device. The memory 130 can beintegrated with the controller 120, or the memory 130 can be externaland remotely coupled to the controller 120. The memory 130 can be, forexample, random access memory (RAM), read only memory (ROM), electronicerasable programmable read only memory (EEPROM), flash memory, or othervolatile or non-volatile memory (i.e., non-transitory computer readablemedia).

The parameter threshold 134 can include a voltage threshold(s),frequency threshold(s) or other different types of thresholds orconditions for use in categorizing an acceptability or unacceptabilityof a monitored electrical parameter of an electrical signal from a powersource. The parameter threshold 134 can be expressed as a quantitativeor qualitative threshold (or condition). While a single parameterthreshold may be employed to differentiate an acceptable (e.g., good) orunacceptable (e.g., bad) state of a monitored electrical parameter, theparameter threshold may include a plurality of unacceptable parameterthreshold ranges and/or a plurality of acceptable parameter thresholdranges to increase the sensitivity of the condition detection/predictionmethodology. Different amounts or weights to increment/decrement thecount value of the counter circuit can be associated with the pluralityof different acceptable and unacceptable parameter threshold ranges.

The count threshold 136 can include a start-count threshold forinitiating an engine start signal to start operation of a power source(or its engine), a stop-count threshold for initiating an engine stopsignal to stop operation of a power source (or its engine), and othercount thresholds for the count value to initiate other actions orpredict other conditions. In various embodiments, the start-countthreshold and the stop-count threshold may be the maximum or minimumvalue (or vice-a-versa) for the counter circuit.

The communication device 150 can be a transmitter, transceiver, signalcircuit or other device, which is able to perform wireless or wirelinecommunications with other remote devices or systems, including but notlimited to the power sources (e.g., the second power source 20) andother equipment in a power distribution system. In some embodiments, thesignal circuit can include a contact which can be opened or closed,under control of the controller 120, to initiate a desired signal to thesecond power source 20. For example, an engine start signal can beprovided when the contact de-energizes and closes, and an engine stopsignal can be provided when the contact energizes and opens.

FIG. 2 illustrates a first graph 200 illustrating a monitored electricalparameter of an electrical signal from a power source over time, and asecond graph 250 showing a count value, which may change over timeaccording to the monitored electrical parameter, in accordance with anembodiment. Example transfer switch operations of the present disclosurewill now be described with reference to FIG. 2 .

In this example, a first power source (e.g., a primary power source) isinitially supplying electric power to a load through an electricalsignal, and the monitored electrical parameter of the electrical signalis voltage.

As shown in FIG. 2 , at time T0, the electrical signal from the firstpower source is sampled by a sensor(s) and the magnitude of the voltageis monitored (e.g., sensed or derived) by a controller using theinformation from the sensor(s). The controller determines that themonitored voltage does not satisfy (or meet) the voltage threshold(e.g., an unacceptable or bad sample). Therefore, in this example, thecontroller increments the count value of the counter circuit by anamount for an unacceptable voltage at T0. At times T1 and T2, thecontroller determines that the monitored voltage of the electricalsignal does not satisfy the voltage threshold, and thus, increments thecount value at those times accordingly. At time T3, the controllerdetermines that the monitored voltage satisfies the voltage threshold(e.g., an acceptable or good sample). Therefore, the controllerdecrements the count value of the counter circuit by an amount for anacceptable voltage. The controller continues to monitor the electricalparameter of the electrical signal over time versus the voltagethreshold to update the count value of the counter circuit. For example,the controller increments the count value at time T4, decrements thecount value at time T5, increments the count value at T6, and finallyincrements the count value at T7 such that the count value satisfies thestart-count threshold. The satisfaction of the start-count threshold mayindicate an imminent problem with the first power source (e.g., apower-flickering event, imminent power outage or failure, or so forth).When the start-count threshold is satisfied, the controller initiatesthe engine start signal to start operation of the second power source(e.g., a secondary power source) and implements other transfer switchoperations including switching the power supply to the load from thefirst power source to the second power source, via a switch. Theswitching operation can be performed after a period of time (which canbe predefined) when or after the second power source has started or islikely to start operation (e.g., turned ON).

In a further embodiment, the count value of the counter circuit cancontinue being updated (e.g., incremented or decremented) over timeaccording to the monitored voltage of the electrical signal from thefirst power source. Should the count value satisfy the stop-countthreshold, the controller can initiate the engine stop signal to stopoperation of the second power source and implement other transfer switchoperations including switching the power supply to the load from thesecond power source back to the first power source, via the switch. Thestop-count threshold can be used to identify or predict the operationalstate of the first power source, e.g., when the first power source is orhas become reliable or stable.

In the example of FIG. 2 , the maximum count value and minimum countvalue can be the start-count threshold and the stop-count threshold,respectively. Furthermore, in this example, the incremented amount(e.g., 4) can be larger than the decremented amount or weighteddifferently than the decremented amount; however, the incremented ordecremented amount can be determined, changed, or customized/tuned. Forexample, the incremented or decremented amount can be selected accordingto various factors, including but not limited to the applicationincluding the load applications, equipment including the power sources,behavior of the power source(s) based on the operational history of thepower distribution system, and other information associated with thepower distribution system. The parameter and count thresholds may alsobe determined, changed, or customized/tuned in a similar fashion. Invarious embodiments, the amounts to increment or decrement and/or thevarious thresholds can be set at the factory, set or changed by theuser, or downloaded to the controller of the automatic transfer switchsystem, and selected to vary the sensitivity of the conditiondetection/prediction methodology as described herein.

While the above example of FIG. 2 monitors a voltage parameter, theautomatic transfer switch system can be configured to implement thetransfer switch operations, including the initiation of the start andstop signals, by monitoring other types of electrical parameters or acombination of electrical parameters for the electrical signal from apower source. For example, the other types of electrical parameters caninclude but is not limited to a frequency of the electrical signal in apolyphase system. The frequency threshold can be an acceptable orunacceptable differential threshold of the frequency between electricalsignals of two different phases. The combination of electricalparameters can include voltage, frequency and/or other types ofelectrical parameters, and may have associated therewith parameterthresholds for the combined parameter or value thereof.

FIG. 3 is a flow chart illustrating example operations of a method 300by which an engine start signal is initiated to start a first powersource (e.g., primary power source) in a power transfer scenario, inaccordance with an embodiment. The method 300 begins at block 302, inwhich a first power source is supplying electric power, via anelectrical signal, to a load. At block 304, a controller monitors anelectrical parameter of the electrical signal from the first powersource. For example, as previously discussed, the controller can monitorthe electrical parameter using information sensed from one or moresensors. At block 306, the controller determines whether the electricalparameter satisfies a parameter threshold. At block 308, the controllerincrements or decrements a count value of a counter circuit, accordingto the determination. At block 310, the controller checks whether thecount value satisfies the start-count threshold. If not, the method 300returns back to block 304. Otherwise, if the count value satisfies thestart-count threshold, the controller initiates a start engine signal tostart operation of a second power source (e.g., a secondary powersource), at block 312. At block 314, the controller can initiate otheractions to transfer responsibility for supplying power to the load fromthe first power source to the second power source. These actions caninclude among other things switching over the power supply to the loadfrom the first power source to the second power source, via a switch.

FIG. 4 is a flow chart illustrating example operations of a method 400by which an engine stop signal is initiated to stop operation of asecond power source (e.g., a secondary power source) in a power transferscenario, in accordance with an embodiment. The method 400 begins atblock 402, in which the second power source is supplying electric powerto a load. At this time, first power source (e.g., a primary powersource) is disconnected, via a switch, from supplying power to the load.At block 404, a controller monitors an electrical parameter of theelectrical signal from the first power source. For example, aspreviously discussed the controller can monitor the electrical parameterusing information sensed from one or more sensors. At block 406, thecontroller determines whether the electrical parameter satisfies aparameter threshold. At block 408, the controller increments ordecrements a count value of a counter circuit, according to thedetermination. At block 410, the controller checks whether the countvalue satisfies the stop-count threshold. If not, the method 400 returnsback to block 404. Otherwise, if the count value satisfies thestop-count threshold, the controller can initiate actions to transferresponsibility for supplying power to the load from the second powersource back to the first power source at block 412. These actions caninclude among other things switching over the power supply to the loadfrom the second power source back to the first power source, via theswitch. At block 414, the controller initiates a stop engine signal tostop operation of the second power source, at block 412.

FIG. 5 is a flow chart illustrating an example method 500 of controllingoperations in a power distribution system. The method 500 begins atblock 502 in which a controller monitors an electrical parameter of anelectrical signal from a first power source associated with supplyingpower to a load. At block 504, the controller determines whether theelectrical parameter satisfies a parameter threshold. At block 506, thecontroller selects to increment or decrement a count value in accordancewith the determination. At block 508, responsive to determining that thecount value satisfies a first count threshold, the controller initiatesa start signal to start operation of a second power source to supplypower to the load.

In the preceding, reference is made to various embodiments. However, thescope of the present disclosure is not limited to the specific describedembodiments. Instead, any combination of the described features andelements, whether related to different embodiments or not, iscontemplated to implement and practice contemplated embodiments.Furthermore, although embodiments may achieve advantages over otherpossible solutions or over the prior art, whether or not a particularadvantage is achieved by a given embodiment is not limiting of the scopeof the present disclosure. Thus, the preceding aspects, features,embodiments and advantages are merely illustrative and are notconsidered elements or limitations of the appended claims except whereexplicitly recited in a claim(s).

For example, it should be understood that the power quality monitoring,detection, and control features, described herein, can be implementedwith devices or systems other than a transfer switch. Such devices orsystems can include but is not limited to a circuit breaker, a powercontrol system, an intelligent electronic device (IED) in a powerdistribution system or other devices or systems employed in a powerdistribution system. Furthermore, various actions can be initiated usingthe detection scheme, described herein, depending on the application.The actions can, for example, include initiating a control signal todisconnect a load by opening a circuit breaker, sending an alarm, orother action to be taken according to the detected power quality of thepower supply.

In addition, the detection scheme, described herein, may also beimplemented by monitoring electrical parameters (of an electricalsignal) other than voltage or frequency. For example, other electricalparameters can include but is not limited to current, total harmonicdistortion, flicker, power, or other parameter(s) from which a powerquality of an electrical signal from a power source may be evaluated.

It should also be understood that the example embodiments disclosed andtaught herein are susceptible to numerous and various modifications andalternative forms. Thus, the use of a singular term, such as, but notlimited to, “a” and the like, is not intended as limiting of the numberof items. Furthermore, the naming conventions for the variouscomponents, functions, characteristics, thresholds, and other elementsused herein are provided as examples, and can be given a different nameor label. The use of the term “or” is not limited to exclusive “or”, butcan also mean “and/or”.

The various embodiments disclosed herein may be implemented as a system,method or computer program product. Accordingly, aspects may take theform of an entirely hardware embodiment, an entirely software embodiment(including firmware, resident software, micro-code, etc.) or anembodiment combining software and hardware aspects that may allgenerally be referred to herein as a “circuit,” “module” or “system.”Furthermore, aspects may take the form of a computer program productembodied in one or more computer-readable medium(s) havingcomputer-readable program code embodied thereon.

Any combination of one or more computer-readable medium(s) may beutilized. The computer-readable medium may be a non-transitorycomputer-readable medium. A non-transitory computer-readable medium maybe, for example, but not limited to, an electronic, magnetic, optical,electromagnetic, infrared, or semiconductor system, apparatus, ordevice, or any suitable combination of the foregoing. More specificexamples (a non-exhaustive list) of the non-transitory computer-readablemedium can include the following: an electrical connection having one ormore wires, a portable computer diskette, a hard disk, a random accessmemory (RAM), a read-only memory (ROM), an erasable programmableread-only memory (EPROM or Flash memory), an optical fiber, a portablecompact disc read-only memory (CD-ROM), an optical storage device, amagnetic storage device, or any suitable combination of the foregoing.Program code embodied on a computer-readable medium may be transmittedusing any appropriate medium, including but not limited to wireless,wireline, optical fiber cable, RF, etc., or any suitable combination ofthe foregoing.

Computer program code for carrying out operations for aspects of thepresent disclosure may be written in any combination of one or moreprogramming languages. Moreover, such computer program code can executeusing a single computer system or by multiple computer systemscommunicating with one another (e.g., using a local area network (LAN),wide area network (WAN), the Internet, etc.). While various features inthe preceding are described with reference to flowchart illustrationsand/or block diagrams, a person of ordinary skill in the art willunderstand that each block of the flowchart illustrations and/or blockdiagrams, as well as combinations of blocks in the flowchartillustrations and/or block diagrams, can be implemented by computerlogic (e.g., computer program instructions, hardware logic, acombination of the two, etc.). Generally, computer program instructionsmay be provided to a processor(s) of a general-purpose computer,special-purpose computer, or other programmable data processingapparatus. Moreover, the execution of such computer program instructionsusing the processor(s) produces a machine that can carry out afunction(s) or act(s) specified in the flowchart and/or block diagramblock or blocks.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality and/or operation of possible implementationsof various embodiments of the present disclosure. In this regard, eachblock in the flowchart or block diagrams may represent a module, segmentor portion of code, which comprises one or more executable instructionsfor implementing the specified logical function(s). It should also benoted that, in some alternative implementations, the functions noted inthe block may occur out of the order noted in the figures. For example,two blocks shown in succession may, in fact, be executed substantiallyconcurrently, or the blocks may sometimes be executed in the reverseorder, depending upon the functionality involved. It will also be notedthat each block of the block diagrams and/or flowchart illustration, andcombinations of blocks in the block diagrams and/or flowchartillustration, can be implemented by special purpose hardware-basedsystems that perform the specified functions or acts, or combinations ofspecial purpose hardware and computer instructions.

It is to be understood that the above description is intended to beillustrative, and not restrictive. Many other implementation examplesare apparent upon reading and understanding the above description.Although the disclosure describes specific examples, it is recognizedthat the systems and methods of the disclosure are not limited to theexamples described herein, but may be practiced with modificationswithin the scope of the appended claims. Accordingly, the specificationand drawings are to be regarded in an illustrative sense rather than arestrictive sense. The scope of the disclosure should, therefore, bedetermined with reference to the appended claims, along with the fullscope of equivalents to which such claims are entitled.

We claim:
 1. A method of controlling operations in a power distributionsystem, comprising: incrementing a count value if an electricalparameter of an electrical signal, from a first power source associatedwith supplying power to a load, satisfies a parameter threshold;decrementing the count value if the electrical parameter does notsatisfy the parameter threshold; and responsive to determining that thecount value satisfies a first count threshold, initiating a start signalto start operation of a second power source to supply power to the load.2. The method according to claim 1, wherein the electrical parameter isvoltage.
 3. The method according to claim 1, wherein the electricalsignal comprises a polyphase electrical signal, and the electricalparameter is frequency.
 4. The method according to claim 1, wherein thecount value is incremented or decremented by an amount according to avalue of the electrical parameter.
 5. The method according to claim 1,further comprising: monitoring the electrical parameter of theelectrical signal from the first power source associated with supplyingpower to the load.
 6. The method according to claim 1, wherein an amountto increment the count value is different from an amount to decrementthe count value.
 7. The method according to claim 1, wherein theparameter threshold comprises a plurality of parameter threshold rangeshaving associated therewith different increment or decrement amounts,the determining operation determines a parameter threshold range for theelectrical signal from the plurality of parameter threshold ranges, andthe selecting operation increments or decrements the count value by anamount associated with the determined parameter threshold range from theplurality of parameter threshold ranges.
 8. The method according toclaim 1, further comprising after initiating the start signal,controlling a switch to transfer responsibility of supplying power tothe load from the first power source to the second power source.
 9. Themethod according to claim 8, wherein the second power source isconnected to supply power to the load, the method further comprising:continuing the performance of the incrementing and decrementingoperations over time to update the count value; and when the count valuesatisfies a second count threshold, initiating a stop signal to stopoperation of the second power source and controlling the switch totransfer responsibility of supplying power to the load from the secondpower source back to the first power source.
 10. An apparatus forcontrolling operations in a power distribution system, comprising:memory; and processor, in communication with the memory, for:incrementing a count value if an electrical parameter of an electricalsignal, from a first power source associated with supplying power to aload, satisfies a parameter threshold; decrementing the count value ifthe electrical parameter does not satisfy the parameter threshold; andresponsive to determining that the count value satisfies a first countthreshold, initiating a start signal to start operation of a secondpower source to supply power to the load.
 11. The system according toclaim 10, wherein the electrical parameter is voltage.
 12. The systemaccording to claim 10, wherein the electrical signal comprises apolyphase electrical signal, and the electrical parameter is frequency.13. The system according to claim 10, wherein the count value isincremented or decremented by an amount according to a value of theelectrical parameter.
 14. The system according to claim 10, furthercomprising: monitoring the electrical parameter of the electrical signalfrom the first power source associated with supplying power to the load.15. The system according to claim 10, wherein an amount to increment thecount value is different from an amount to decrement the count value.16. The system according to claim 10, wherein the parameter thresholdcomprises a plurality of parameter threshold ranges having associatedtherewith different increment or decrement amounts, the controllerdetermines a parameter threshold range for the electrical signal fromthe plurality of parameter threshold ranges, and the controllerincrements or decrements the count value by an amount associated withthe determined parameter threshold range from the plurality of parameterthreshold ranges.
 17. The system according to claim 10, wherein thecontroller is further configured to control a switch to transferresponsibility of supplying power to the load from the first powersource to the second power source, after initiating the start signal.18. The system according to claim 17, wherein the second power source isconnected to supply power to the load, the controller being furtherconfigured: to continue the performance of the monitoring, determiningand selecting operations over time to update the count value, and whenthe count value satisfies a second count threshold, to initiate a stopsignal to stop operation of the second power source and to control theswitch to transfer responsibility of supplying power to the load fromthe second power source back to the first power source.
 19. Anon-tangible computer readable medium storing computer code, which whenexecuted by a processor, implements a method of controlling operationsin a power distribution system, comprising: incrementing a count valueif an electrical parameter of an electrical signal, from a first powersource associated with supplying power to a load, satisfies a parameterthreshold; decrementing the count value if the electrical parameter doesnot satisfy the parameter threshold; and responsive to determining thatthe count value satisfies a first count threshold, initiating a startsignal to start operation of a second power source to supply power tothe load.
 20. The non-tangible computer readable medium according toclaim 19, wherein the method further comprises: monitoring theelectrical parameter of the electrical signal from the first powersource associated with supplying power to the load.